There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

I know a ten-letter word in the English language which can be typed using only the top rows of the computer keyboard.

John has played 50 ODI's and his average is 50. How many runs should he score in his 51st ODI, so that his average score jumps to 51?

I have two sand hourglasses:
1. A 7 minute one and
2. An 11-minute one.

Using just these 2 sand hourglasses, how can I measure time as 15 minutes?

By including only four matchsticks in below picture, you have to make "Four Triangles And Two Squares"

How can you spell "White of an egg" in one word?
Hint: I know you can spell coke, poke, and joke.

Can you count the number of squares in the figure below?

How many triangles are there on the puzzle below?

In the Mexico City area, there are two Houses H1 and H2. Both H1 and H2 have two children each.
In House H1, The boy plays for Mexico Youth academy and the other child plays baseball.
In House H2, The boy Plays soccer for his school in Mexico and they recently have a newborn.

Can you prove that the probability of House-H1 having a girl child is more than that of House-H2?

If a shopkeeper can only place the weights on one side of the common balance. For example, if he has weights 1 and 3 then he can measure 1, 3 and 4 only. Now the question is how many minimum weights and names of the weights you will need to measure all weights from 1 to 1000? This is a fairly simple problem and very easy to prove also.